Fluid system



FLUID SYSTEM Lyle L. Mylex-aine, Piper City, ll.

Filed Apr. 10, 1958, Sel'. No. 727,669

2 Claims. (Cl. Gil- 52) This invention relates to a self-containedpressure dfferentiating and uid metering device. It is describedhereafter in connection with a hydraulic system of a farm tractor, inwhich it has particular practical application, but it is to beunderstood that the dev-ice has numerous other applications.

Modern farm tractors are customarily equipped with hydraulicallyoperated draw bars. The hydraulic systems by which the draw bars areoperated frequently are provided with pumps of such character as tocirculate a large amount of hydraulic iluid at a relatively lowpressure, for example ten to fourteen gallons per minute at thirty totwelve hundred pounds per square inch. Such a system has a number ofadvantages but it also has a serious disadvantage in that it cannotsatisfactorily be used to operate other hydraulic equipment, such as ahydraulically operated power steering system, because such otherequipment frequently operates at a dilferent pressure. For this reason,it has been customary to install a separate and independent hydraulicsystem for the power steering at considerable expense, rwith a separatepump capable of delivering a relatively small amount of duid at arelatively high pressure.

One of the objects of this invention is to provide a simple, compactdevice whereby a part of the energy of iiuid which is moving under ahead is utilized to pump a portion of the same fluid at a pressuredifferent from the head under which the iluid was moving.

Other objects will become apparent to those skilled in the art in thelight of the following description and accompanying drawing.

In accordance with this invention generally stated, a device is providedin which uid moving under pressure is directed against vanes theeffective area of which is selectively variable, in such a way that thevanes are caused to move and at the same time the eiective area of someof the vanes is decreased. A portion of the uid initially directedagainst the vanes is in turn impelled by the vanes with diminished area.

vIn the drawing, lFigure l is a sectional View taken along the line 1-1of Figure 2, showing a device constructed in accordance with oneembodiment of this invention in a hydraulic system of a tractor, thehydraulic system being shown diagrammatically; and

lFigure 2 is a sectional view taken along the line 2-2 of Figure 1.

Referring now to the drawing for an illustrative embodiment of thisinvention, reference numeral 1 represents a hydraulic system for a farmtractor, including a pump 2, a draw bar raising mechanism with the usualcontrol valve and bypass arrangement, all indicated diagrammatically at3 in Figure l, a pressure pipe 4 leading from the discharge side of thepump 2 and a return pipe 5 connected, by way of the draw bar raisingmechanism 3, to the suction side of the pump 2.

In the hydraulic system 1, connected to the pressure pipe 4 at one sideand to the return pipe 5 at the other, ,is a pressure diierentiating andduid metering device nited States Patent 0 constructed in accordancewith one embodiment of this invention. The device 10 comprises a casing12 and a rotor 50. The casing 12 is made up of a block 13 and a coverplate 14 bolted to the block 13 by means of studs 15'. The studs 15 takeinto tapped holes 16 in the block I3, passing through holes 17 in thecover plate 14. The block 13 is provided with an inlet passage 19,tapped to take a threaded end of the pressure pipe 4, and an outletpassage 20, tapped to take a threaded end of the return pipe 5.Intermediate the inlet passage 19 and outlet passage 20 is a -rotorcavity 22. The rotor cavity 22 is made up of a circular inner journalcavity 23, a circular outer journal cavity 24, and a vane receivingchannel 25. The vane receiving channel 25 lies between the journalcavities 23 and 24. It'communicates with the inlet passage 19 and theoutlet passage 20, between which it is substantially concentric with thejonrnal cavities 23 and 24. It also connects the outlet passage 20 witha discharge passage 26. The discharge passage 26 has branches 27 and 28.A discharge pipe 30 is screwed into a threaded section of the dischargepassage 26. Between the outlet passage 20 and the branch 27, the vanereceiving channel 25 is also concentric with respect to the journalcavities 23 and 24. Between the edge of the branch passage 27 nearestthe outlet passage 20 and the edge of the branch passage 28 farthestfrom the outlet passage 20, the radial depth of the channel 25 decreasesuntil at the edge of the branch passage 28 most remote from the outletpassage 20, the radii of the channel 25 and the journal cavities 23 and24 are identical, as shown in Figure 1. In the quadrant between thebranch passage 28 and the inlet passage 19, the radius of the channel 25remains the same. A passage 36 in the block 13 communicates with theinlet passage 19 and with the center of the inner journal cavity 23.

The rotor 50 is disc-shaped and is proportioned rotatably to fit withinthe journal cavities 23 and 24. In the embodiment shown, it is providedwith eight radial slots or recesses 51 in each of which a vane 52 isslideably mounted. Each vane 52 is biased outwardlyV by a spring 53seated at one end in `a bore 54 in the bottom of the slot 51, and at theother end in a recess 55 in the vane 52. An axial passage 5S in therotor 50 communicates at one end with the passage 36 and at its otherend with branch passages 59 each connected with the bottom of a bore 54.

The vane receiving channel 25 is wide enough closely to receive thevanes 52 of the rotor 5G. It is wider than the passages 19 and 20 alongthe area of communication with those passages as shown in Figure 2. Theradial depth of the channel 25 with respect to the journal cavities 23and 24 and the rotor 50, between the inlet passage 19 and the outletpassage 29, is less than the length of the vanes 52 between theiroutside edges and the bottom of the recesses 55 against which thesprings 54 bear. 'Ihe radial depth of the channel 25 between the outletpassage 20 and the branch passage 27 of the discharge passage '26 isless than the radial depth of the channel 25 between the inlet passage19 and the outlet passage 20, so that the volume of liuid :which can beaccommodated by the channel 25 between successive vanes is less betweenthe outlet passage 20 and the branch passage 27 than it is between theinlet passage 19 and the outlet passage 20.

In the embodiment shown, the discharge pipe 39 is connected with a powersteering apparatus 35, indicated diagrammatically in Figure l, fromwhich the fluid ilows through a differential Valve 37, also shownsomewhat diagrammatically in Figure 1. The differential valve shownutilizes the bias of a spring 38 to maintain a greater pressure in thepower steering system 35 than exists in the draw bar system. A steeringsystem return pipe '39 connects the differential valve 37 with thereturn pipe i In the operation of the illustrative embodiment shown, thesystem isilled with hydraulic uid, generally an oily liquid.V Whenthe-pump 2 is started, the `viiuid `isforced through 'the pressure'pipeV4. The `uid moves through thel inlet passage 19 and, acting uponYaffvaneg52 begins to rotate the-rotor 50.` A small part ofV the fluidiwill -pass-V through the passages 36 andSSlinto` the-branchpassages-59, hence to the inside ofthe-recesses or slots 51 where itwill tend to force the vanes 52-outwardly, assisting the springs 53. Asthe rotor, 50 begins; to turn,

and the iiuid in the system begins `to circulate, most 'of 1` the fluid'passingY through the channel 25 between fthe inlet passage 19and theoutlet ,passagey 20 -will bedischarged into the outlet passage 20,Yhence tvo-,the return pipe 5. A part ofthe uid, however, will be-forcedinto the channel 25 between the outlet-passage 20 and creases, so'thatthe iiuid` between the vanes is forced through the branch passage 27and,` when the leading vane has begun to pass the branch passage 28,through the branch passage 28 into the discharge passage 26.

The pressure which is producedin the line 30, is dependent upon thedifferential valve 38, so long as the product of the pressure and thevolume of fluid through the power steering system is less than theproduct of the pressure and the volume of fluid flowing through thechannel 25 between the inlet passage 19 and the outlet passage 20, lessthe power losses due to friction of the rotor, line loss and the like.In the drawing of the illus trative embodiment shown, the radial depthof the channel 25 between the inlet passage 19 and the outlet passage 20is about three times that of the channel between the outlet passage 2Gand the branchy27. If the various losses to which reference has beenmade were disregarded the device should be capable of producing apressure at the discharge passage 26 of slightly less than three timesthe pressure in the inlet passage 19, i.e., the pressure at Vwhich theuid is delivered from the pump 2. In practice, in order to ensure freecirculation of the fluid, a multiplication of one and one-half to twotimes is considered reasonable.

In practice, both the draw -bar system and the power steering systemwill be provided with a reservoir of uid under pressure. Y

The advantages of the device of this invention ywill be immediatelyapparent to tractor owners. With the aid of this simple device, theordinary low pressure pump, which has ample capacity to handle bothsystems, can be utilized for Vboth the draw bar operating system and apowerV steering system, at a small fraction of the cost of theinstallation of a totally separate power steering system and pump.

As a specific example of a device of this invention used with ahydraulic system on an ordinary farm tractor,

Y in which a pump delivers ten to fourteen gallons per minute ofhydraulicV fluid at thirty to twelve hundred pounds per square inchpressure, the overall size of the block and cover plate can be six bysix by two and onehalf'inches. The inlet passage 19 may have-a bore ofapproximately seven-eighths of aniinch, T he rotor 50 i may beapproximately four inches in diameter and two inches wide, and the slots51 approximately one and threequarters of an inch deep. The vanes 52vmaybe approximately one and one-half inches long and approximately one andthree-quarters toY two inches wide; The channel 25 between the inletpassage 19and the outlet passage 20 may beV approximately one-half ofanginchk deep 4and approximately one and three-quarters to two incheswide. The depth of the channel 25 between the outlet passage 20 and thebranch passage 21 may be approximately threeeighths of an inch deep. Thebore of the outlet passage 20-may be approximately seven-eighths of Ianinch, and of the discharge passage 26, one-half of an inch. A pressureof thirty to twelve hundred poundsV perrsquare inch may b e producedV bythe `differential valve 37, although, when the control valves Yto thedrawbar raising cylinder and the powermsteering cylinders, not hereshown, are in neutral position,the pressure regulatorA (by-pass) valvesofthe `steering and drawbar raising mechanisms are normally arrangedtoropen and allow ythe pump to circulate iuid at low pressure.

The bore of the outlet passage 20 can either be made smaller than thebore of the inlet passage 19 or a suitable choke can be used so that thecombined volumes of the fluid delivered to the discharge vpassage 26'andthe outlet passage 20 is the same as the volume of uid delivered to theinlet passaget19. This ensures that the channel 25 betweenV the outletpassage 2 0 and the discharge passage 2,6 isvm'aintained full.

In the device described, the hydraulic uid itself acts to lubricate the'Various parts. While the rotor fits closely withinrthe rotorcavity,there isY still enough clearance, for example from .Q01 to .0005 inch,between the at faces ofthe rotor disc and the -iiat face dening thebottom of the inner journal cavity 23 onthe one side and the cover plateproviding the bottom of the outer ljournal cavity 24 onY the other, andbetween the peripheral surfaces of the rotor and journal cavities, topermit some of the iiuid to get between them to accomplish thelubrication. Y v t `When liquids which have little or no lubricatingqualities are to be handled, it may be-necessary to mount the rotor on aIshaft journaledV in conventional sealed bearings which may be of anyof'numerous suitable kinds known to the art. The block, cover plate androtor may be complementarily grooved toY form races to receive ballbearings, or the rotor may be provided with stub shafts on eitherside,journaled in bearing cavities in the block and cover plate. It canbe seen that the `device of this invention has numerous applicationsbeyond the hydraulic system of a tractor. Itcan be used not only asapressure differentiator but as a metering or proportionating device. Ifthe channel 25 is` kept filled, a volume of fluid bearing the samerelationship to the total volume as the depth of the channel 25 betweenthe outlet passage 20 and the discharge passage 26 bears to the depth ofthe channel 25 between the'inlet passage 19 and the outlet passage 20will be delivered to the discharge passage 26. Thus, water, oil, orother liquids which are pumpedthrough a pipe under pressure, or gas, canbe metered olf by the use of this device. Y Y

Numerous variations in the construction of the device of this invention,within lthe scope of the appended'claims will occur to those skilled inthe art in the light of the foregoing disclosure. For example, theeffective surface area of the vanes may be varied in ways other thanmaking them slide radially within the slots in the rotor. If

the vanes are made of rubber or other resilient material, they need notslide in radial slots in the rotor, but can be iixed on the periphery ofthe rotor. This arrangement is particularly useful in adevice akin tothe hydraulic ram. l VYHaving thus described the invention, what isclaimed K and desired to be securedby Letters Patent is:

`caribe utilized to operate the power steering` apparatus,

comprising a casing having a rotor cavity, an inlet passage to saidrotor cavity connected to the discharge side of the pump, an outletpassage to said rotor cavity connected, by way of the drawbar mechanism,to the suction side of said pump and a discharge passage connected tothe power steering system; a rotor rotatably mounted within said cavity,a plurality of vanes mounted in said rotor for radial sliding movementand extending closely but slideably within a channel in said cavity,said channel extending in an arc substantially concentric with the rotorbetween the inlet passage and the outlet passage and between the outletpassage andthe discharge passage, said channel connecting said passagesrespectively, the depth of said channel between the outlet passage andthe discharge passage being substantially less than the depth of thechannel between the inlet and outlet passages and the depth of thechannel between the discharge passage and the inlet passage beingsubstantially less than the depth of the channel between the outlet anddischarge passages.

2. In a system wherein fluid ows in a conduit connecting a high pressurearea to a low pressure area, a device of the character described,wherein the kinetic energy of the owing uid is utilized to multiply thepressure of a portion of the fluid itself, said device consisting of acasing having a rotor cavity deiined by a wall, an inlet passagecommunicating with said uid conduit on the high pressure side and withsaid rotor cavity, an

outlet passage communicating with said uid conduit on the low pressureside and with said rotor cavity, and a discharge passage communicatingwith said rotor cavity, said outlet passage lying between the dischargevand inlet passages; a rotor rotatably mounted within said rotor cavity,and vanes mounted on said rotor, said vanes being biased to bear againstthe wall defining the rotor cavity and adapted to move in response tovariations in the contours of said wall, said wall being substantiallyconcentric with the rotor between the inlet passage and the outletpassage, and between the outlet passage and the discharge passage anddefining a channel with said rotor, the cross sectional area of thechannel between the inlet and outlet passages being greater than thatbetween the outlet and discharge passages, and said rotor and walldefining a constricted section between the discharge passage and theinlet passage of less cross sectional area than that of the channelbetween the outlet passage and the discharge passage.

References Cited in the file of this patent UNITED STATES PATENTS1,296,356 Bey Mar. 4, 1919 2,832,199 Adams et al Apr. 29, 1958 FOREIGNPATENTS 892,075 France J an. 3, 1944

